Power shift mechanism



L. A. LANG.

POWER SHIFT MECHANISM.

APPLICATION FILED MAY 1?. 1917.

1,328,437. Patented Jan. 20,1920.

3 SHEETS-SHEET 2.

TED STATES PATENT OFFICE.

LINCOLN A. LANG, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE'NORTH'ERN TRUSTCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS, TRUSTEE.

rowan SHIFT MECHANISM.

Specification of Letters Patent.

I Patented Jan. 20, 1920.

Application filed May 17, 1917. Serial No. 169,217.

To all whom it may concern,

Be it known that I, LINCOLN A. LANG, a

citizen of the United States, residing at Chiplied to manyditferentuses, is particularly space; to provide a construction-whichemwelladapted for use in connection with that general class of apparatusknown as servo motor follow-up mechanisms; that is to say,power-operated mechanism, the extent of movement of which is determinedby the position of a manually adjustable controlling device. 1

Among the salient objects of the invention are to provide power-shiftmechanism of the class described, so organized that the number of partsneeded to perform the various functions of the construction is reducedto a minimum; to provide a construction so arranged that it will occupya minimum bodies as far as possible a straight line movement of thecontrolling connection and of the main actuating member; to provide afluid-operated construction embodying a valve arrangementsuch thatimproper adjustment of the valve or the packings therefor does notimpair the effectiveness of the device; to provide a fluid-operatedarrangement of the class described organized so as to facilitateadmission and expulsion of the actuating fluid; to provide a fool-proofarrangement'of the character described which may be operated andmaintained by relatively unskilled labor; to provide an arrangement ofthe class described which shall be extremely simple, neat, andeconomical in construction; to provide an arrangement of the classdescribed which shall be extremely sensitive and quick to respond tochanges of adjustment or unbalanced conditions,.while at the same timebeing extremely stable and -not subject to hunting or other improperpable of being operated incase ,9!- power failure; and, in general, toprovide an improved construction of the character referred to. v

In the drawings, which accompany this application, I have illustrated,as a specific embodiment of my invention, a locomotive, the reversinggear for which is actuated by apparatus embodying said invention. Insaid drawings- Figure 1 is a side elevation of a locomotive showing thepower shift mechanism in its general location and arrangement as appliedto the locomotive;

Fig. 2 is an end elevation looking forward into the cab of the,locomotive shown in Fig. 1;

Fig. 3 is a side elevation of the principal part of the device with itsoperating connections; Fig. 4 is an end elevation of the cylinder andvalve-actuating mechanism therefor, looking from the left of Fig. 3; p

Fig. 5 is a vertical longitudinal section taken throughthe duplexpiston, with its associated valve apparatus;

F ig. 6 is a section taken on the line 6-6 of Fig. 5;

Fig. 7 is a perspective view of one of the exhaust valves; and Fig. 8 isa section taken on the line 8-8 of Fig. 5.

Referring to the drawings, 10 represents as a whole an ordinary steamlocomotive having the usual boiler, cab, frame, and driving gearoperated by cylinders not shown in the drawings. The reversing gear forthe said cylinders is actuated by means of a bell crank 11, betweenwhich and the hand-lever 12 is interposed my improved power-shiftmechanism. 13 represents the cylinder of the device, which is suitablysecured to the boiler of the locomotive by, means of feet or lugs 1 4'(see Fig. 4), the piston 15 of the said cylinder being connected to thebell crank 11 by means of a pair of suitable rods or links 16. As shownbest in Fig. 5, the piston 15 is of considerable length, the ends 17and1 8 thereof being enlarged to fit the cylinder and equipped with aseries of piston rings, as at 19, which maintain the ends of the pistonin fluid-tight engagement with the interior walls of the cylactuatingmember; to provide a device cainc er. The extreme'length of the cylinderof the piston effectually prevent cramping of the piston in thecylinder, due to cross stresses which may be applied to the piston. Inorder to facilitate connection of the links 16 with the piston, thelatter has centrally journaled therein a horizontal transverse shaft orpin '20 which is journaled in a boss-like partition 21 which separatesthe two hollow ends of the piston. The rear ends of the links 16 arepinned upon the ends of the said shaft 20, which ends project through apair of slots '22 cut in the sides of the cylinder 13. It is understoodthat the length of the slots 22 is somewhat greater than the totalstroke of the piston in its cyl- 1n er.

On the rear end of the cylinder I prefer" to bolt a small bracket 23which forms a 'fulcrum for the pivotally mounted lever 24.

The upper end of the said lever 24 is pivotally connected by means of alink, 25 with the lower end 26 of the hand-lever 12, the latter beingpivoted on a shaft or pin 27 suitably supported in the cab of thelocomotive. The hand-lever 12, which may be moved into any desiredposition, is locked in place by a suitable spring-pressed dog whichcotiperates in the usual manner with notches 28 formed in the arc of afixed quadrant 29. It will be manifest that movement of the hand-lever12 will move the lower end of the lever 24 in an obvious manner, thesaid lower end of the lever 24 being connected to the control mechanismnow to be described.

It will be observed that the lower end of the lever 24 is pivotallyconnected by means of a link 30 with a block 31 (see also Fig. 5), saidblock having an axially horizontal boss 32 fixedly secured to ahorizontal shaft 33 by means of suitable set screws 34. On the ends ofthe shaft 33 are bolted, by means of nuts 35, a pair of tappet plates 36and 37, said 'tappet plates 36 and 37 having adjustably secured thereintwo pairs of horizontal tappet rods 38, 39, 40, and 41. The rod 33 isarranged to slide in alined'holes in a pair of bosses at the lower endof the valve casting designated as a whole 44. Said valve housing 44 iscarried principally beneath the cylinder 13, as shown in Fig. 3, and iscentrally bolted to the middle stem of the piston 15 by means ofsuitable studs or screws 45. The lower wall of the cylinder 13 iscentrally slotted, as shown at 46. in order to admit the stem orconnecting piece 47 of the valve housing which, as previously stated, isbolted to the central stem of the piston.

As shown best in Fig. 6. the valve-actuating tappets 38, 39, 40, and 41operate a set of four valves of puppet type, viz., an intake valve 48for the left hand end of the cylinder, an exhaust valve 49 for the righthand end of the cylinder, an exhaust valve 50 for the left hand end ofthe cylinder, and an 1ntake valve 51 for the right hand end ofthecylinder. As shown in Fig. 7, each of said valves 48, 49, 50, and 51,comprises the usual mushroom head 52, a cylindrical stem or bodyportion53, the latter having a series of grooves 54 milled therein, eachof the series of grooves commencing at a different distance from themushroom head 52 so that when the valve is actuated it will to a certainextent throttle the flow of fluid, by reason of the fact that thevarious grooves of the series will one by one become graduallyefl'ective to pass fluid through the valve. it being understood that themain body or stem part 53 of the valve is a fairly good fit in the boredhousing 55.

The valves 48, 49, 50, and 51 are normally held in engagement with theirseats by reason of a series of coil springs 56, 57, 58. and 59. theouter ends of which fit around short projections 60 on the ends of thevalves, the other ends of the springs being positioned around circularbosses 61 and 62 which divide the valve pockets 63 and 64, and 65 and66. In view of the fact that the valves 49 and 50 are exhaust valvesonly. the spaces 67 and 68 being in free communication with theatmosphere through exhaust apertures, shown at 68 in Fig. 5. it isunnecessary to provide packed glands for the tappet rods 39 and 40.which slide. freely in the solid plugs 71 and 72. By referring to Fig.6, it willalso be seen that there is an opening or space 73 between theends of the tappets 39 and 40 and the small steel plugs or studs 74inserted in the ends of the valves 49 and 50. Such spaces are providedto permit some latitude of movement of the valveactuating tappetswithout opening the exhaust valves. the amount of this latitude beingdetermined by the nature of the work to be accomplished.

Pressure fluid. preferably compressed air. is supplied to the cylinderthrough a pipe 75 bolted to, and with its axis parallelto the axis of,the cylinder 13. so as to permit free sliding movement of the slidingsupply tube 76. air-tight slidable engagement between said inner pipe 76and outer pipe 75 being established bymeans of a suitable gland orstuffing box 77 on the end of the stationary pipe 75. The rear end ofthe sliding supply tube 76 is screwed into the step-47 of the valvehousing and communi cates with .the central pocket, indicated in dottedlines at 78 in Fig. 6. said pocket 78 communicating by means oftransverse passages T9 and 80 with the pockets 63 and 66 associated withthe intake valves 48 and 51. The space 81 is connected to the space 64by means of a longitudinal ofi'set conduit 82. said conduit 82 alsocomnmnicating with the left hand end of the hollow piston 1 by means ofan inclined port or conduit 83 in the stem 47 of the valve housing.Simisurrounded by suitable packed glands 87 and 88.

Describing the operation of the apparatus, it will be understood, inviewofthe prior description, that when the main control stem 33 is movedlongitudinally relative to the valve housing 44, a pair of valves at oneof the ends ofthe valve housing will be opened by the corresponding pairof tappets, whereas the other pair of valves at the other end of thevalve housing will remain closed, due to the coil springs and thepressure forcing said valves tightly against their seats. Under ordinarycircumstances, the twoends of the c linder 13 andthe spaces .containedwithin t e hollow ends of the piston 15 will be filled with compressedair at substantially the same pressure, the piston being thus held inbalanced relation. If, however, it be desired to change the position ofthe reyersing gear by moving the link 16in the di-' rection of the arrow89 (see Fig. 3), the link 30 will be moved in the same direction byshifting the hand lever 12 in the direction of the arrow 90. As soon asthe hand lever 12 is moved in such direction, the link 30 will be thrustforward, and,'by reason of the connecting block 31,. the main controlrod 33 will move forward, actuating the tappets 38 and 3.9 to open theinlet valve 48 and the exhaust valve 49. As has been previouslydescribed, the exhaust valve 49 is connected with the right hand end ofthe cylinder through the space 65, longitudinal conduit 85, and inclinedconduit 86. Consequently, when said valve 49 opens, the pressure in theI right hand end of the cylinder will be relieved permitting theunreduced pressure in the left hand end of the cylinder to move thepiston forwardly. At the same time, by. reason of the factthat theintake valve 48 has also been opened, compressed air will pass throughthe supply tube 76, into space 78, to transverse conduit 80, through thetransverse conduit 79, into the space 63, through the valve 48, into thespace 81, and thence through thelongitudinal ofi'set conduit 82 andconduit 83 into the left hand end of the cylinder.

The piston moving forward will of course carry forward the reversinglink 16 in an obvious manner.

The extent of movement of the link 16 will be determined by the movementof the hand-lever 12, for the reason that the relative position of thecontrol rod. 33 and the control rod 33 forwardly four inches, the

piston 15 will also move forward a distance of four inches until themovement of thevalve housing 44 has moved the parts into the samerelative position as is shown in Fi 5. It will be understoodthat thereis su cient play between the ends of the control block 32 and the bosses42 and 43 to permit a proper amount of opening of the various valves,due to the relative'movement of the tappe'ts in the valve housing. Ifthe hand-lever 12 be jerked over too quickly for the piston to respondinstantly, the block 32 will of course strike one of the bosses 42 and43 and open the corresponding valves to the maximum extent, whichvalves, however, will be at'once closed as soon as the piston 15 hasresponded and moved the valve casting into the normal position, as

shown in Fig. 5. 7

When the handle is locked, any tendency toward improper movement of thepiston, due to unbalanced forces exerted by the links 16, areautomatically prevented by reason of the fact that the control shaft 33is positively positioned by the hand-lever, and any slight movement ofthe piston in either direction will automatically open such valves aswill immediately exhaust fluid from the proper end of the cylinder tocause the piston to at once, move back into its normal position. Suchtendency toward improper movement is of course also to a certain extentarrested by reason of the fact that the end of the cylinder from whichthe piston is moved is at that time sealed, such movement thus causingthe pressure to drop below normal, the other end being opened up to fullpressurex The device in this respect is particularly sensitive andresponds instantly to resist the tendency of the piston.

' improper movement of the piston, and similarly to any proper movementof the handlever.

By reason of the fact that the piston and the member to be moved, movein the same straight line as the control rod, 33, which same time, allparts of the device are readily accessible for purposes of repair orrenewa It will be observed that improper adjustment of the glands aroundthe tappet stems will have no effect in destroying the effectiveness ofthe arrangement, for the reason that the springs controlling the valvesare incased within the valve housing and operate directly upon thevalves to close the same, and do not have to overcome the packingfriction as in the ordinary type of puppet valve with the outwardlyprojecting valve stem. The only effect of excessive tightening of one ofthe gland packings is to cause an excess of the gland friction,necessitating the use of slightly more power applied to the hand-lever12 in order to shift the valve.

In devices of the general character described, it is frequentlyadvantageous to be able to operate the reversing link or othercontrolled member by hand in case of a partial or total failure of thepower supply. In my improved apparatus, this emergency manual control isreadily effected by reason of the fact'that if the piston does not atonce respond to the opening of the valves by the movement of thehand-lever, delay in the movement of such piston will'cause the block 31to strike one of the bossesin which the rod 33 slides, and thus thepiston and parts controlled thereby may be moved by exerting directpressure thereon through-the hand-lever 12 and linkage connecting thesame'with the block 31. Ordinarily of course the power responds quicklyenough to the movement of the hand-lever to prevent said block 31 fromengaging with the said bosses.

In the event that it is desired to replace the use of compressed airwith steam, for instance in ship-steering apparatus, it is of courseundesirable to discharge the exhaust steam from the apparatus directlyinto the atmosphere, or room in which the apparatus is installed. Insuch case, it is a simple matter to connect the exhaust apertures to acommon closed conduit communicating with a telescopic ipe arrangedparallel with and similar to t e arrangement used for conducting thepressure fluid to the apparatus.

In developing my invention I encountered seemingly insurmountabledifiiculties in the Way of using an expansive element, such as air orsteam, in a shift mechanism of the class described. The principaldifliculty encountered was that due to the failure of the piston to cometo rest or to position itself in conformity with the position of thedifferentially controlled valve-moving mechanism positioned by thehandle. In certain cases and under certain conditions, the, piston wouldover-run its true position, as determined by the setting of the handle,and

cause the differentially controlled valves to open in a direction tomove the piston back valve linkage, heavy, and in some cases extremelysudden, stresses are imposed upon the link which actuates the link ofthe reversing gear. Obviously, the tendency of the piston to hunt in itscylinder would be much increased by the said stresses, particularly ifthe same were of a vibratory character and of a vibration frequencycorresponding to the vibratory movement ofthe control piston hunting inits cylinder. This and other difliculties are overcome in my im rovedapparatus.

11 the first place, as shown, Iemploy an exceedingly long piston,chambered out at each end in order to provide extremely large clearancespaces compared with the net piston displacement, thus making thecushioning effect due to the movement of the piston in the cylinder,aside from the valve control, substantially uniform for all positions ofthe piston in the cylinder; whereas, if the piston be made withcomparatively small clearance spaces, the difference in the cushioningaction of the cylinder between posi; tions at the end of the center ofits stroke is quite marked, necessitating different adjustments of thevarious parts to overcome the hunting tendency.

In the second place, Iadjust the inlet tap pets in such a way as toprovide no clearance between the tappets and the inlet valves controlledthereby when the tappet control shaft 33 is in its normal position.Under normal conditions, such arrangement maintains substantially fullpressure in each end of the cylinder at all times, the slightestmovement of the piston or control shaft serving to open substantiallyone or other .of the air inlet valves.

In the third place, I provide considerable clearance, as shown at 73,between the exhaust valves and their actuating tappets.

Such clearance prevents the exhaust valves i-inch movement of the handcontrol will always result in a certain definite movement' of the valvemechanism, assuming the piston to be stationary, which ratios andconditions are constant throughout all positions of the piston. Inaddition thereto, the piston and the hand-lever control are so arrangedthat movement of the valve mechanism, or a certain movement of either ofthem, is identical with that due to a similar movement of the otherpart. This is extremely important in insuring identical operation of thevalve mechanism in all parts of the piston stroke,so mething which isnot obtained by the use of floating lever differentials.

In the fifth place, the valves, being of the puppet type, are free fromleakage and operate instantly and positively, although the valveopenings are initially restricted as described.

The mechanism possesses, among other advantages, one, particularly,which is not possessed by similar devices which have heretofore beenbrought to my attention, viz., the movement of the power-controlledparts is communicated mechanically to the handle by reason of the factthat the parts may be so adjusted that a fairly considerable force isnecessary to cause relative movement of the control shaft 33 and thehousing. This is possible by reason of the inherent friction in themovement of the various parts, including the friction of the tappet rodsin the glands and the resistance due both to the valve-closing springsand the fact that the valves open against pressure, particularly theexhaust valves. Thus, if the device be used for steering a ship and thesteering wheel be connected to the block '31, through suitable chainsand gearing (reversible), the rudder being suitably connect- 50 ed tothe piston, pressure applied to the rudder through the waves, currents,or by reason of the fact that the ships course is being changed, will befaithfully communicated to the steering wheel, assuming of course thatthe friction of the steering wheel connections is less than theresistance of the valvemoving mechanism. This feature of my invention isof almost inestimable value in ship steering, as it enables thequartermaster or p1lot to feel the rudder, a feature, so

far as I am aware, not possessed by any other power steering mechanismwhich has hitherto been brought to no attention.

Theinvention is capab e of being embodied in a large number of differentforms for various different purposes to suit individual plans. Hence,the invention is not intended to be limited by the specific details ofthe described construction, but must i be interpreted in a broad sensewhile referring to the appended claims.-

I claim a 1. In a device of the class described, the combination of apilot member, a cylin der, a piston for said cylinder, a source ofmotive fluidfor moving said piston, valve mechanism for controlling saidmotive fluid, spring means normally tending to prevent movement of saidvalve mechanism, and a controlling connection between said pilot memberand said valve mechanism, the arrangement being such that resistancepreventing actuation of the valvemechanism is suflicient to causemovement of the pilot member'without operating said valve mechanism whenthe pistonis moved by external forces.

2. In a servo-motor follow-up device, the combination of a handle, amember controlledthereby, a pair of spaced apart cylinder ends, pistonmeans therefor connected together and constituting with said cylinderends in effect a double-acting cylinder provided with a piston, a valvehousing carried by, movable with, and forming an integral part of, saidpiston means and interposed between said cylinder ends, valve mechanismcarried by said housing for admitting and discharging fluid to and fromthe said cylinder ends to move said piston whereby said controlledmember is operated, and a control member for said valve mechanismmechanically connected to said handle and positively movable thereby ina direction in line with the direction of movement of said housing, thearrangement being such that move ment either of the piston or of thehandle will cause operation of said valve mechanism.

3. In a servo-motor follow-up device, the combination of a pair ofspaced apart coaxially alined cylinder ends, an elon ated piston membercommon to both of sai cylinder ends ahd constituting with said c linderends in effect a double-acting cylin er equipped with a piston, alaterally projectmg valve housing carried by, movable with,

in a direction in line with the direction of' movement of said housing,the arrangement being such that movement either of the piston or of thehandle will cause operat on of said valve mechanism.

' limit of the piston stroke, a housing mechanically connected to saidpiston and provided with valve means for admitting and discharging fluidto and from the cylinder to move said piston, and a control member forsaid valve means movable in a direction parallel with the movement ofsaid valve means and actuated by the controlling member.

5. In a device of the class described, the combination of a cylinderhaving an apertured side wall, a piston in said cylinder, valvemechanism traveling with said piston, a pilot member for actuating saidvalve mechanism and a member projecting through said apertured wall'forconnecting the load with the piston.

6. In a device of the class described, the combination of a powercylinder having an apertured side wall, an elongated piston in saidcylinder having an intermediate portion exposed through said aperture,valve mechanism secured to the exposed part of said piston controllingfluid for moving the piston in opposite directions, and a pilot memberfor operating said valve mechanism and movable in a directionsubstantially parallel with the cylinder axis.

7. In a device of the class described, the combination of a powercylinder having an mama? movable in a direction substantially parallelwith the cylinder axis, and a member also projecting through saidapertured wall for connecting the load with the piston.

8. In a servo-motor device, the combination of a pair of opposedcylinder ends having an intermediate opening, a double-ended pistonassociated therewith, a valve housing xed upon and movable with anintermediate part of said piston and having a part extending throughsaid intermediate opening, valve mechanism in said housin controllingmotive fluid for operating said piston, and a pilot member for actuatingsaid valve mechanism and movable in a direction substantially arallelwith the piston axis.

9. In a devlce of the class described, the combination of an elongatedpiston, a cylinder having its side Wall cut away to expose anintermediate portion of said piston, an externally arranged valvehousing secured to said exposed piston part and freely exposed to theatmosphere, a source of motive fluid for moving said piston, valvemechanism on said housin for controlling said fluid, and a pilot mem ermovable in a direction substantially parallel to the cylinder axis foractuating said valve mechanlsm.

LINCOLN A, LANG.

